Background: Myo-inositol given to preterm infants with respiratory distress has reduced death, increased survival without bronchopulmonary dysplasia, and reduced severe retinopathy of prematurity in two randomized trials. Pharmacokinetic (PK) studies in extremely preterm infants are needed before efficacy trials.
Methods: Infants born in 23-29 wk of gestation were randomized to a single intravenous (i.v.) dose of inositol at 60 or 120 mg/kg or placebo. Over 96 h, serum levels (sparse sampling population PK) and urine inositol excretion were determined. Population PK models were fit using a nonlinear mixed-effects approach. Safety outcomes were recorded.
Results: A single-compartment model that included factors for endogenous inositol production, allometric size based on weight, gestational age strata, and creatinine clearance fit the data best. The central volume of distribution was 0.5115 l/kg, the clearance was 0.0679 l/kg/h, endogenous production was 2.67 mg/kg/h, and the half-life was 5.22 h when modeled without the covariates. During the first 12 h, renal inositol excretion quadrupled in the 120 mg/kg group, returning to near-baseline value after 48 h. There was no diuretic side effect. No significant differences in adverse events occurred among the three groups (P > 0.05).
Conclusion: A single-compartment model accounting for endogenous production satisfactorily described the PK of i.v. inositol.